JP3226720B2 - Combustion control device for two-cycle engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combustion control device for a two-cycle engine.

[0002]

2. Description of the Related Art In engines such as automobiles and outboard motors, controlling the air-fuel ratio improves the combustion state of the engine, thereby improving engine output and reducing harmful components in exhaust gas. I am trying to do it. In the control of the air-fuel ratio, it is common to install an exhaust gas sensor to detect the amount of oxygen in the exhaust gas, obtain the air-fuel ratio from the detected value, and control the fuel supply amount so that this matches the target air-fuel ratio. It is.

On the other hand, a two-stroke engine has a scavenging stroke for discharging burned gas by fresh air.
In a cycle engine, there is a blow-by phenomenon in which fresh air is mixed in exhaust gas. Therefore, when the oxygen concentration in the exhaust gas flowing in the exhaust pipe is detected, an accurate air-fuel ratio cannot be obtained. Therefore, in the air-fuel ratio control of the two-cycle engine, the oxygen concentration of the burned gas in the combustion chamber is detected, and the air-fuel ratio is obtained based on the detected oxygen concentration. In the detection of the oxygen concentration, adjacent cylinders having a phase difference are connected to each other through a detection passage, an O ₂ sensor is interposed in the passage, and burned gas flows from one cylinder to the other cylinder. It is conceivable to collect the gas to be detected.

[0004] In the present invention, the burned gas means a gas containing only a combustion gas without a blow-by gas, or a gas in a case where the content of the blow-by gas is such that the oxygen concentration detection is not so hindered. The term "exhaust gas" means a mixed gas of blow-through gas and combustion gas. Also,
The mixture refers to a mixture of fresh air and fuel.

[0005]

However, when the above-described method of interposing an O ₂ sensor in a detection passage connecting adjacent cylinders is adopted in a multi-cylinder engine, the exhaust port of each cylinder is connected to one exhaust passage. In a combined exhaust system, since the distance from each exhaust port to the exhaust passage differs for each cylinder, the intake air amount differs for each cylinder, and a sensor is required for each cylinder, which complicates the structure. There is a problem that costs increase.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and has been made in consideration of the above-described problems. Even in the case of a multi-cylinder engine, the combustion of a two-stroke engine capable of optimally controlling the air-fuel ratio of the engine without providing a sensor for each cylinder. It is intended to provide a control device.

[0007]

According to the first aspect of the present invention, there is provided a combustion control apparatus for a two-stroke engine having an exhaust system in which exhaust ports of respective cylinders are gathered into one exhaust passage. Air-fuel ratio calculating means for calculating the air-fuel ratio of the air-fuel mixture based on the detection value from the O ₂ sensor for detecting the oxygen concentration of the burned gas not containing, so that the obtained air-fuel ratio becomes the target air-fuel ratio, Basic fuel supply amount control means for controlling the fuel supply amount to the specific cylinder; and an engine operating state based on map data in which the ratio between the air amount to the specific cylinder and the air amount to the remaining cylinders is stored in advance. And a correction fuel supply amount control unit that corrects the value of the fuel supply amount to the specific cylinder according to the ratio to obtain the fuel supply amount to the remaining cylinders. And that To have.

A second aspect of the present invention is characterized in that, in the first aspect, the air-fuel ratio calculating means includes a stoichiometric O ₂ sensor.

According to a third aspect of the present invention, in the second aspect, the correction fuel supply amount control means controls the fuel so that the target air-fuel ratio of each cylinder other than the specific cylinder becomes richer than the target air-fuel ratio of the specific cylinder. It is characterized in that it is configured to control the supply amount.

A fourth aspect of the present invention is characterized in that, in the first aspect, the air-fuel ratio calculating means includes a linear O ₂ sensor.

[0011] The invention of claim 5, in any one of claims 1 to 4, the air-fuel ratio calculating means comprises an O ₂ sensor for detecting the oxygen concentration in the burnt gas, the O ₂ sensor position A detection passage communicating between one cylinder having the phase difference and the other cylinder is provided in the middle of the detection passage, and an introduction port of the detection passage is located between the exhaust port and the scavenging port of the one cylinder. , The discharge port is located closer to the bottom dead center than the exhaust port of the other cylinder, and the inlet port and the discharge port are
Open simultaneously during a certain period after the start of the exhaust stroke of one cylinder and a certain period before the start of the compression stroke of the other cylinder,
The phase difference is set so that the burned gas in one cylinder flows toward the other cylinder during this period.

[0012]

According to the first aspect of the present invention, the air-fuel ratio is determined from the oxygen concentration of the burned gas that does not include the blow-through fresh air of the specific cylinder, and the determined air-fuel ratio of the mixture is determined. Is a feedback control of the fuel supply amount to the specific cylinder so that the target air-fuel ratio becomes the target air-fuel ratio, and the fuel supply amount at this time is corrected according to the ratio of the respective air amounts supplied to the specific cylinder and the remaining cylinders. Thus, the fuel supply amount to each of the remaining cylinders is obtained.

As described above, the specific air cylinder is controlled so as to attain the target air-fuel ratio, and the remaining cylinders are supplied with the fuel supply amount to the specific cylinder corrected in accordance with the variation in the air amount. Thus, by detecting the air-fuel ratio of one cylinder, it is possible to control all cylinders to a combustion state with an appropriate air-fuel ratio. Here, the target air-fuel ratio of each of the remaining cylinders can be set to a desired value by correction according to the above-mentioned variation in the air amount, and optimal control can be realized.

According to the combustion control apparatus for a two-cycle engine of the second aspect of the invention, the stoichiometric O ₂ sensor is provided in the specific cylinder to detect the air-fuel ratio, so that the cost can be reduced and the structure can be simplified. it can. In addition, the specific cylinder is controlled near the optimum air-fuel ratio because the A / F range detected by the stoichiometric O ₂ sensor is narrow, but the remaining cylinders are controlled according to the target air-fuel ratio freely set, that is, the optimum air-fuel ratio. Fuel ratio control is possible.

In general, in a two-cycle engine, the burned gas stays in the cylinder, so that the optimum air-fuel ratio is on the richer side than the A / F value that can be detected by the stoichiometric O ₂ sensor.
Therefore, according to the combustion control apparatus for a two-stroke engine of the third aspect of the invention, the fuel supply amount is controlled such that the target air-fuel ratio of each cylinder other than the specific cylinder becomes richer than the target air-fuel ratio of the specific cylinder. Therefore, it is possible to control the optimum air-fuel ratio for the specific cylinder near the target air-fuel ratio and for the remaining cylinders.

According to the combustion control device for a two-stroke engine of the fourth aspect of the present invention, since the specific cylinder is provided with a linear O ₂ sensor to detect the air-fuel ratio, the specific cylinder and each of the remaining cylinders are also detected. Optimal air-fuel ratio control is possible.

According to the fourth aspect of the present invention, one cylinder having a phase difference and the other cylinder communicate with each other only during a predetermined period before the start of a compression stroke when one cylinder starts an exhaust stroke. connected by detection passage, since the interposed an O ₂ sensor for detecting the oxygen concentration in the burnt gas in the middle of the passage, it is possible to detect the air-fuel ratio of only Ryakusunde燃gas containing almost no blow gas, The accuracy of the feedback control can be improved, and the combustion state of the engine can always be stabilized.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIGS. 1 to 6 are views for explaining a combustion control device for a two-stroke engine according to a first embodiment of the present invention. In FIG. 1, the device of this embodiment is applied. Schematic configuration diagram of a three-cylinder two-stroke engine for an outboard motor,
FIG. 2 is a schematic diagram for explaining the mounting structure of the O ₂ sensor, FIG. 3 is a characteristic diagram showing the relationship between the crank angle of the No. 2 cylinder and the in-cylinder pressure, and FIG. 4 is a graph showing the output of the O ₂ sensor and the target A / F value. FIG. 5 is a characteristic diagram showing the variation of the intake air amount for each cylinder depending on the engine speed, and FIG. 6 is a functional block diagram.

In FIG. 1, reference numeral 1 denotes an engine for a three-cylinder, two-stroke outboard motor having a vertically mounted crankshaft, in which a piston 3 is slidably disposed in a cylinder bore 3a of a cylinder block 2, and the piston 3 is connected to a connecting rod. 4 is connected to the crankshaft 5. In the AA cross section in FIG. 1, indicates a cylinder number, and the phase difference between the cylinders is set to 120 °.

A cylinder head 6 is mounted on the mating surface of the cylinder block 2, and a spark plug 7 is inserted into a combustion recess formed in the cylinder head 6. 2a is an exhaust port and 2b is a scavenging port. The three exhaust ports 2a are gathered in one exhaust passage. The cylinder head 6 is provided with a pressure sensor 31 for measuring an in-cylinder pressure, and the crankshaft 5 is provided with an angle sensor 33 for detecting a crank angle (engine speed). A crank chamber 8 is provided on the side of the cylinder block 2 opposite to the head. The crank chamber 8 is provided with a temperature sensor 32 for measuring intake air temperature or engine temperature, and a pressure sensor 34 for measuring crank chamber pressure.

A bypass passage (detection passage) 4 is provided between the numbered cylinder (the other cylinder) and the numbered cylinder (one cylinder).
0 is provided, and an O ₂ sensor 35 for detecting the air-fuel ratio of the burned gas is provided at an intermediate portion of the passage 40. In this case, as shown in FIG. 2, the introduction port 65 of the bypass passage 40 is connected between the opening timing position H1 of the exhaust port 2a of the cylinder No. and the opening timing position H2 of the scavenging port 2b, for example, with the exhaust port 2a. It is arranged to be opened and closed at the same time. Further, the discharge port 68 of the passage 40 is opened at an advanced angle side (bottom dead center side) from the closing timing position H1 'of the exhaust port 2a of the cylinder No., for example, immediately before opening the scavenging port 2b, and immediately after closing. The inlet 65 and the outlet 68 are opened and closed by the pistons 3 of the respective cylinders.

Here, as shown in FIG. 3, the in-cylinder pressure P2 of the numbered cylinder and the in-cylinder pressure P1 of the numbered cylinder fluctuate with a phase difference of 120 ° between the two cylinders. In addition, the introduction port 65 is connected to the exhaust port 2a in the cylinder number.
From the open timing crank angle A to the close timing crank angle B. On the other hand, the discharge port 68 is opened from the open timing crank angle (not shown) of the scavenging port 2b of the cylinder No. to the crank angle D immediately after the close timing.
Therefore, the inlet port 65 and the outlet port 68 are simultaneously opened during the period of the crank angles A to D, and during this time, the gas flows from the cylinder number to the cylinder number due to the pressure difference. The symbol E indicates a closing timing crank angle of the exhaust port 2a of the cylinder number.

Here, when the inlet port 65 is arranged between the exhaust port 2a and the scavenging port 2b of the cylinder No. 2 when it is arranged closer to the top dead center than the exhaust port 2a, it is compressed in the compression process of the cylinder No. 2. This is because the fresh air to be escaped through the passage 40, and the compression efficiency is reduced. In addition, if it is located closer to the bottom dead center than the scavenging port 2b, the introduction port 65 and the discharge port 68 are opened at the same time, and the period in which the burned gas flows from the cylinder number to the cylinder number becomes shorter.

Since the positions of the inlet 65 and the outlet 68 of the passage 40 are set as described above, when the inlet 65 is opened immediately after the start of the exhaust stroke by the piston 3 of the numbered cylinder, the outlet 68 of the numbered cylinder is closed. Since the piston 3 is still opened by the piston 3 located immediately before the start of the compression stroke, the burned gas in the cylinder number is introduced by the pressure difference between the cylinder number and the cylinder pressure between the cylinder numbers simultaneously with the opening of the introduction port 65. The gas flows through the passage 40 from the port 65 to the discharge port 68, and the sensor 35 measures the amount of oxygen in the burned gas. Since the discharge port 68 is closed immediately before the scavenging port 2b is opened in the cylinder No., the burned gas flowing through the passage 40 does not include blow-through fresh air. Therefore, the sensor 35 can measure the amount of oxygen in the burned gas that does not include the blow-by fresh air, and can detect the air-fuel ratio of the burned gas that does not include the blow-by fresh air.

Further, since the passage 40 is formed to have a uniform diameter without a constricted portion, carbon or sludge is generated due to incomplete combustion when the engine 1 is operated at an extremely low speed such as a trolling operation of the outboard motor. Even so, the inside of the passage 40 is not blocked by the carbon or the like.

Further, the inlet port 65 and the discharge port 68 of the passage 40 are opened and closed by the pistons 3 of the cylinder number and the cylinder number, and are simultaneously opened only during the crank angles A to D as described above. That is, since one of the openings is almost always closed, the burned gas in any one of the cylinders does not flow backward from the inlet 65 or the outlet 68 into the passage 40.

Further, since the passage 40 has a simple structure, the fluid resistance is small, and therefore, for example, the air-fuel ratio for each cycle can be detected even during excessive operation, and the optimum air-fuel ratio control can be performed during excessive operation. .

In the above embodiment, the case where the engine 1 is a three-cylinder two-stroke engine has been described. However, since there is a phase difference between the cylinders, the inlet 65 and the outlet 68 of the passage 40 are set at appropriate timing positions. V type 4
The present invention is also applicable to a two-stroke engine of a cylinder or a V-type six cylinder.

The O ₂ sensor 35 is a so-called stoichiometric sensor capable of detecting only the air-fuel ratio in a narrow range near the stoichiometric air-fuel ratio, and its output is represented by a characteristic line 7-1 in FIG.
As shown in the above, when A / F is ab near the stoichiometric air-fuel ratio, a'b 'is obtained. In this embodiment, the target A / F value is variably controlled in the range of (a to b) according to the engine operating state. Note that a linear sensor having a linear output characteristic as shown by a characteristic line 7-2 in FIG. 4 may be used as the O ₂ sensor. When this linear sensor is used, the variable range of the target A / F can be greatly expanded.

An intake passage 10 is connected to each of the crank chambers 8 through a cylinder bore 3a. A reed valve 11 for preventing backflow of the intake air is disposed near the opening of the intake passage 10 near the crank chamber. Each of the intake passages 10 is provided with an injector 12 for injecting fuel into the intake passage, and a fuel supply device 13 is connected to the injector 12. The injector may be common to all cylinders. In this case, it is provided at the gathering portion of the intake manifold. A throttle valve 15 is provided in the intake passage 10.
, Ie, the throttle angle is detected by the sensor 41. Further, the outboard motor body 50 includes:
A trim angle detection sensor 42 for detecting the trim angle β is provided.

The engine 1 includes an ECU 3 as a control unit.
0 is provided. The said ECU 30, the cylinder pressure sensor 31, intake air temperature detection sensor 32, a crank angle sensor 33, the crank chamber pressure detecting sensor 34, O ₂ sensor 35, the back pressure detecting sensor 36, an engine temperature sensor 3
7, throttle angle detection sensor 41, atmospheric pressure detection sensor,
Each detection signal of the shift switch, the cooling water temperature detection sensor, and the engine vibration sensor is input.

As shown in FIG. 6, the ECU 30 controls the fuel of the specified cylinder (numbered cylinder) so that the air-fuel ratio of the air-fuel mixture obtained from the value detected by the O ₂ sensor 35 becomes the target air-fuel ratio. It functions as basic fuel supply amount control means 60 for performing feedback control of the fuel injection amount from the injection valve 12. The ECU 30 also serves as an air amount detecting means 71 for obtaining a ratio (air amount variation) between the air amount to the numbered cylinder and the other air amount to the numbered cylinder according to the engine speed in the engine operating state. Working,
Specifically, the map diagram of FIG. 5 showing the air amount variation for each engine speed is stored. Further, it also functions as a corrected fuel supply amount control means 72 for correcting the fuel supply amount to the cylinder number according to the map value and obtaining the fuel supply amount to the cylinder number. It should be noted that the map data shown in FIG. 5 is obtained in advance by experiments, and the intake air amount for each cylinder decreases as the engine speed increases, while the air amount to the cylinder number decreases. The amount of air to the air has a tendency to increase.

Next, the operation of this embodiment will be described.
In the present embodiment, in the specific cylinder (number cylinder),
The A / F value of the burned gas is detected by the stoichiometric O ₂ sensor 35, and the fuel injection amount is feedback-controlled so that the detected value becomes the target air-fuel ratio (range a to b in FIG. 4). Further, in the remaining cylinders (and No. cylinders), the fuel injection amount to the specific cylinder is corrected based on the map data in FIG. 5 and supplied. In this case, the cylinder No. is controlled near the optimum air-fuel ratio due to the narrow detection range of the stoichiometric sensor.

In this case, for example, the engine speed 3000
At the rpm and the throttle fully open operation region, as is clear from FIG. 5, the air amount of the cylinder No. is larger than the air amount of the cylinder No.
The air amount in the cylinder number is small. Therefore, in the case of the same A / F of each cylinder, the fuel amount is corrected so that the fuel amount to the cylinder number is larger than the fuel amount to the cylinder number and the fuel amount to the cylinder number is smaller.

As described above, in the combustion control apparatus for a two-stroke engine according to the present embodiment, the stoichiometric sensor detects the air-fuel ratio of the cylinder number. The cylinder can be controlled to the optimum air-fuel ratio according to the target air-fuel ratio, so that the combustion state of the engine can be controlled to an appropriate air-fuel ratio without providing a sensor for each cylinder.

The amount of fuel supplied to the remaining cylinders (No. cylinder) is controlled even if the target air-fuel ratio of the specified cylinder (No. cylinder) becomes richer than the target air-fuel ratio of the specific cylinder (No. cylinder). good. In this case, in general, in a two-cycle engine, the burned gas stays in the cylinder,
_{Since the} optimal air-fuel ratio is on the rich side of the A / F value that can be detected by the _two sensors, the cylinder No.
The cylinder No. can be controlled to the optimum air-fuel ratio according to the target air-fuel ratio.

Next, the second aspect of the present invention will be described.
A combustion control device for a two-cycle engine according to an embodiment will be described. It should be noted that the apparatus of the present embodiment is the same as the O ₂ apparatus of the first embodiment.
Since a linear type O ₂ sensor is applied to the sensor 35, description of the configuration is omitted.

In the combustion control device of this embodiment, a linear sensor having a linear output characteristic as shown by a characteristic line 7-2 in FIG. 4 is used as the O ₂ sensor 35.

As described above, since the linear sensor is used as the O ₂ sensor 35 in the present embodiment, the variable range of the target A / F is greatly expanded as compared with the case where the stoichiometric sensor is used. Therefore, it is possible to control the optimal air-fuel ratio in accordance with the target air-fuel ratio also in the above-mentioned cylinder, and thus, it is possible to perform the optimal air-fuel ratio control also in the above-described specific cylinder and other cylinders. Can be controlled to an appropriate air-fuel ratio.

In the above embodiment, the case where the O ₂ sensor is provided in the middle of the detection passage connecting one cylinder to the other cylinder has been described. However, other O ₂ sensor installation methods can be adopted. It is. That is, one end of the passage connected to the cylinder No. is connected to a pressure accumulating chamber having a cross-sectional area larger than the cross-sectional area of the passage, and the O ₂ sensor faces the pressure accumulating chamber, and the already stored gas in the pressure accumulating chamber. A method of detecting the oxygen concentration of the combustion gas can be adopted. Here, as a method of providing a passage for discharging the burned gas guided to the pressure accumulation chamber, the passage is connected to another cylinder.
A method of connecting to the exhaust passage or returning to the own cylinder (numbered cylinder) using the inlet side passage into which the burned gas flows as it is can be adopted. By doing so, the degree of freedom in providing the discharge passage, that is, the degree of freedom in layout can be increased.

[0041]

As described above, in the combustion control apparatus for a two-stroke engine according to the first aspect of the present invention, the air-fuel ratio is determined from the oxygen concentration of the burned gas that does not include fresh blow-through air of a specific cylinder. By controlling the basic fuel supply amount to the specific cylinder so as to achieve the target air-fuel ratio and correcting the value of the basic fuel supply amount according to the ratio of the air amount to each cylinder, the remaining cylinders To the fuel supply to
By detecting the air-fuel ratio of one cylinder, there is an effect that all the cylinders can be controlled to the optimum air-fuel ratio or near the optimum air-fuel ratio.

In the combustion control apparatus for a two-stroke engine according to the second aspect of the present invention, the air-fuel ratio of a specific cylinder is detected by a stoichiometric O ₂ sensor. Can be controlled to an optimum air-fuel ratio or a state close thereto.

In the combustion control apparatus for a two-stroke engine according to the third aspect of the present invention, the fuel supply amount is controlled such that the target air-fuel ratio of the cylinders other than the specific cylinder becomes richer than the target air-fuel ratio of the specific cylinder. There is an effect that the combustion state of all cylinders can be controlled to the optimum air-fuel ratio.

Further, in the combustion control apparatus for a two-stroke engine according to the fourth aspect of the present invention, since the air-fuel ratio of a specific cylinder is detected by the linear O ₂ sensor, the variable range of the target A / F value can be greatly increased. By providing a sensor for one cylinder, the air-fuel ratio of all cylinders can be controlled to the optimum air-fuel ratio.

In the combustion control apparatus for a two-stroke engine according to the fifth aspect of the invention, one of the cylinders having a phase difference is communicated with the other cylinder only during a predetermined period before the start of the exhaust stroke and the other cylinder is started before the start of the compression stroke. connected by detection passage, in the middle of the detection passage, is provided with the O ₂ sensor for detecting the oxygen concentration in the burnt gas, it is effective to detect the air-fuel ratio of only the burned gas containing no blow fresh air, Thus, the feedback control based on the air-fuel ratio of only the burned gas has an effect of always stabilizing the operating state of the engine.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a combustion control device of a two-cycle engine according to one embodiment of the present invention.

FIG. 2 is a schematic diagram for explaining a mounting position of a detection passage of the apparatus of the embodiment.

FIG. 3 is a characteristic diagram showing a relationship among a crank angle of a cylinder No., an in-cylinder pressure, and opening and closing of a detection passage in the apparatus of the embodiment.

FIG. 4 shows the output of the O ₂ sensor and the target A /
FIG. 4 is a characteristic diagram showing a relationship with an F value.

FIG. 5 is a characteristic diagram showing a variation in an intake air amount for each cylinder depending on an engine speed of the apparatus of the embodiment.

FIG. 6 is a functional block diagram of the device of the embodiment.

[Description of Signs] 2a Exhaust port 2b Scavenging port 30 ECU (basic fuel supply amount control means, air amount detection means, correction fuel supply amount control means) 35 O ₂ sensor (air-fuel ratio calculation means) 40 detection passage 65 inlet 68 Outlet Remaining cylinder (other cylinder) Specific cylinder (one cylinder)

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-57-122144 (JP, A) JP-A-3-149330 (JP, A) JP-A-5-44544 (JP, A) JP-A-5-44544 59986 (JP, A) JP-A-4-325748 (JP, A) JP-A-1-315633 (JP, A) JP-A-4-21742 (JP, U) (58) Fields investigated (Int. ⁷ , DB name) F02D 35/00-45/00

Claims (5)

(57) [Claims] 1. A combustion control device for a two-stroke engine equipped with an exhaust system are gathered into one exhaust passage of the exhaust port of each cylinder, not including blow fresh air of a particular cylinder already
To the detection value from the O ₂ sensor that detects the oxygen concentration of the combustion gas
Air-fuel ratio calculation means for calculating an air-fuel ratio of the air-fuel mixture based on the fuel-air mixture; basic fuel supply amount control means for controlling a fuel supply amount to the specific cylinder so that the obtained air-fuel ratio becomes a target air-fuel ratio ; Air volume to specific cylinder and air volume to each remaining cylinder
Air amount detecting means for determining the ratio of the fuel supply to the specific cylinder from the map data stored in advance according to the operating state of the engine, and correcting the value of the fuel supply amount to the specific cylinder according to the ratio. combustion control apparatus of a two-stroke engine, characterized in that a corrected fuel supply amount control means for calculating a fuel supply amount to each cylinder of Ri Rizan. 2. The combustion control device for a two-stroke engine according to claim 1, wherein said air-fuel ratio calculation means includes a stoichiometric O ₂ sensor. 3. The fuel supply amount control device according to claim 2, wherein the correction fuel supply amount control means controls the fuel supply amount such that the target air-fuel ratio of each cylinder other than the specific cylinder becomes richer than the target air-fuel ratio of the specific cylinder. 2 characterized by the following configuration.
Cycle engine combustion control device. 4. The method according to claim 1, wherein said air-fuel ratio calculating means includes a linear O ₂ sensor.
Cycle engine combustion control device. 5. The method according to claim 1, wherein the air-fuel ratio calculating means detects an oxygen concentration of the burned gas.
_The O ₂ sensor is provided in the middle of a detection passage that connects one cylinder having a phase difference and the other cylinder, and an introduction port of the detection passage is provided for the one cylinder. The exhaust port is located between the exhaust port and the scavenging port, the exhaust port is located on the bottom dead center side of the exhaust port of the other cylinder, and the inlet port and the exhaust port are located in the exhaust stroke of one cylinder. The phase difference is set so as to open simultaneously during a certain period after the start and a certain period before the start of the compression stroke of the other cylinder, and during this period, the burned gas of one cylinder flows toward the other cylinder. A combustion control device for a two-stroke engine.